DRINKing wAter resilient management comBining process anaLyses, CFD and innovative sEnsor monitoring

Due to a progressive change in worldwide environmental perception, great attention is currently devoted to specific pollutants in water, both of natural and anthropic origins, that can have severe implications on human health even in very low concentrations and that are frequently characterized by a long life-time that leads to the possibility of bioaccumulation in the food chain. The monitoring and efficient removal of the pathogens from water is indeed among the highest priority of the society, based on the fact that contaminated water supply can rapidly expose a large number of people to the transmission of diseases. For those reasons, it is of fundamental importance to preserve drinking water quality in distribution systems and connected installations, limiting bacterial regrowth by maintaining, as most common approach, an adequate disinfectant residual in the pipelines. Since in Italy the most used disinfectant is sodium hypochlorite, this approach has to be carefully tuned considering the toxicity of chlorine residual and the potential of toxic and carcinogenic disinfection by-products (DBPs) formation. The challenge connected to the removal of pollutants from contaminated water resources and to the control of bacterial regrowth has received new perspectives nowadays from the fact that the majority of drinking water treatment plants (DWTPs) have been designed in the past and need now to be upgraded to comply with recent quality standards. These are not only related to ¿daily normal¿ conditions but also to specific events, as EXPO, which ask for higher amount of drinking water to be distributed and are subjected to the risk of terrorist actions. It is therefore important that: 1) each treatment unit runs efficiently in removing target pollutants, saving chemicals and energy; and that 2) the water quality achieved at the Point-Of-Entry (POE) is maintained along the full distribution system, especially with reference to opportunistic pathogens, that is the most serious problem associated to regrowth. Another important challenge is the rapid, reliable and affordable detection of alteration of water quality both for operation monitoring and emergency alarming. The present project is aimed at defining an integrated approach for the retrofitting of existing disinfection tanks combining process analysis, modeling, CFD (Computational Fluid Dynamics) simulations with innovative and miniaturized sensors, connected in a network able to provide on-line monitoring and real-time feedback for the optimization of the disinfection processes. These sensors will be integrated in a single platform that we call ¿smart pipe¿, which can be embedded in the tank or in any pipe section to realize a stand-alone (but networkable) multi-purpose intelligent device. The sensor node will be flexible with respect to both installation mode and detection capability. In fact this open platform will house different types of detectors, starting from conductivity and pH sensors, and eventually upgraded with sensors for specific chemical compounds (residual chlorine) and pollutants (THMs) as well as with bio-analytical sensors. These compact units can be installed not only at the inlet and outlet of the treatment tanks, but also along the distribution network, permitting a real-time and distributed detection of the water quality. The smart pipe will also be equipped with miniaturized electrodes to monitor the formation of deposits and biofilm and slime in the pipes which reduce the inner pipe diameter, supporting the plant managers in tuning process operations and scheduling maintenance interventions.